Several devices and systems already exist to aid in the removal of thrombetic material. These include simple aspiration tube type devices using vacuum syringes to extract thrombus into the syringe, simple flush-and-aspirate devices, more complex devices with rotating components the pull in, macerate and transport thrombetic material away from the distal tip using a mechanical auger, systems that use very high pressure to macerate the thrombus and create a venturi effect to flush the macerated material away.
All of the devices described above have limitations as a result of individual design characteristics. For example, simple aspiration catheters off ease of use and rapid deployment but may become blocked or otherwise inoperable when faced with older, more organized thrombetic material. Such devices must be removed and cleared outside the body and then re-inserted into the vasculature, which lengthens the time needed for the procedure and increases the opportunity to kink the catheter shaft. Such kinks may reduce performance by decreasing the cross-sectional area of the catheter or may render the device inoperable. The use of a syringe to provide vacuum, moreover, may increase the risk of operator error by not preventing the operator from applying positive pressure to the aspiration lumen and thereby expelling loose embolic material into the patient vasculature.
Mechanical rotary devices use an auger to grab and carry the thrombus away from the target area. Some create transport force via vacuum bottles while others create differential pressure at the distal tip of the device with the auger acting as a low pressure pump. These devices typically work slowly and offer the physician no feedback as to when the device should be advanced further into the lesion.
Flushing type devices include manual flush type devices in which the physician manipulates a hand-driven pump to provide flowing saline at the tip of the device to break up and aspirate the thrombus material, which may introduce performance variations based on the ability of the physician to consistently pump the device over the duration of the procedure. Flushing devices also include high pressure flushing devices that macerate the thrombus and then, using a vortex created by the high pressure fluid, transport the emulsified thrombetic material to a collection bag. These devices are effective at removing all levels of thrombetic material, but the pressure created by the device is so great that its action against certain vessel walls may interrupt the heart muscle stimulation mechanism and creates a bradycardia event in certain patients that requires a pacing lead to be placed in the patient prior to use. Further, interacting with the thrombetic material outside of the catheter may allow loose material to escape the capture mechanism.
Thus, a need remains for improved thrombus removal capability particularly for systems that have increased reliability, are more benign and offer greater feedback capabilities.